Study On Damage Characteristics Of Shipboard Structures By Near-free Surface Explosion Sequence Loads

Underwater explosion can release huge heat in a very short time and its high-pressure impact and bubble pulsation can cause devastating damage to structures in water such as ships.Underwater contact explosion is more destructive,anti-ship weapons directly hit the ship will damage the internal equipment and a large number of casualties,resulting in the loss of combat effectiveness or even sinking of the ship.Because of the near field of underwater explosion in complex near the free surface boundary conditions,special of explosion load,caused by structural response has strong nonlinear characteristics,especially the condition of the load sequence,can bring great difficulties to the research,at present,for nearly free surface under load sequence of structural damage is still not fully be revealed,the influence of loading sequence close at the free surface,the author of this paper is of great significance to study the damage characteristics of structure,mainly includes the following contents:(1)Establish numerical simulation models,including the simplified contact explosion model of the slab structure,the calculation model of load characteristics and the simplified model of the hull compartment.Based on the hull plate structure,the influence of grid size on the calculation results was verified.The grid size of the simulation model in this paper was determined according to the calculation results.Through the numerical simulation of shock wave load,the dynamic characteristics of single source and double source blast wave load near the free surface are obtained.Based on the hull hull calculation model,the structural damage of the hull under the single source shock wave load in free field and near free surface is simulated,and the structural damage characteristics of the single source blast shock wave load on near free surface are obtained through comparative analysis.(2)Through the simulation of bubble load,the dynamic characteristics of single source and double source bubbles near the free surface are obtained,including the water mound and jet shape of bubbles near the free surface.Based on the calculation model of hull compartment,the damage characteristics of single source bubble load under free field and near free surface are calculated,and the damage characteristics of structure under bubble load near free surface are obtained.According to the model,the damage characteristics of dual source shock wave load and dual source bubble load to the cabin structure are calculated respectively.(3)Based on the simulation model of the hull cabin,the damage characteristics of the cabin structure caused by the near-free surface explosion sequence load are studied.By setting different conditions of the initiation time sequence of two detonation sources,the damage characteristics of the cabin structure caused by the sequence load are obtained according to the comparative analysis of the calculation results.